Added a way to handle 4096/4096 and 0

[Alopalao]

Related to mef_eline PR #258

Summary

From MatchDLVLAN.as_of_tlv(), self.value now can be non-existent VlanId.OFPVID_NONE
From MatchDLVLAN.from_of_tlv(), tlv.oxm_value now can handle the any case with oxm_value = '4096/4096'

Local Tests

Installing this EVC through mef_eline api:

{
    "name": "my evc1",
    "dynamic_backup_path": true,
    "enabled": true,
    "uni_a": {
        "tag": {"tag_type": 1, "value": "any"},
        "interface_id": "00:00:00:00:00:00:00:01:1"
        },
    "uni_z": {
        "tag": {"tag_type": 1, "value": "untagged"},
        "interface_id": "00:00:00:00:00:00:00:02:1"
        }
}

Does not trigger consistency check loop (alien, delete, missing, install) with different values for the UNI tags. Confirming that the de-serialization is working as desired.

[viniarck]

A conditional introduced doesn't look right to me, if you could double check. I left more information in the comment. Thanks.

[viniarck]

@Alopalao this is getting close to land, could you also update the changelog and also add explain which local tests you've run to confirm this? Let's also add e2e tests to cover these cases before merging this, specially since it's protocol dependent, so the earlier we have this cov on OvS with e2e tests the better. Thanks

[viniarck]

@Alopalao I'll leave this PR pre-approved.

When kytos-ng/kytos-end-to-end-tests#210, feel free to merge it as well. In this PR here, the only small remaining changes are a suggestion in the changelog, and maybe the extra unit test, but since you're unit test is already covering maybe we don't need that either, I'll leave it up to you.